1. Field of the Invention
The invention relates to devices for controlling the output of rotary compressors, which devices have a regulating flap valve and a check valve in a common housing, the regulating flap valve controllably changing the passage cross section of the suction duct of a rotary compressor and the check valve being located behind the regulating flap valve in the direction of flow.
2. The Prior Art
It is known to change the cross section of the passage of the suction duct of a rotary compressor using a built-in regulating flap valve so as to adjust the output of the rotary compressor according to individual requirements. Independent thereof, it is in most cases also necessary with compressors of this type to be able to tightly close the suction duct after shutting the compressor down so that the sealed-off medium will not flow back, since it contains in many cases oil that has been injected for lubrication or cooling.
A device of this type is disclosed in DE 34 47 797 C2, for example, wherein the element to prevent back-flow and the controllable throttle are designed as a flap valve and wherein they are arranged one behind the other in a common housing and in the same flow path, which make minor pressure losses possible at optimum operation of the two valves, independent from one another. Especially as a result of the lateral swiveling position of the check valve, which is biased by means of a weight or a spring in the closing direction, there is required in this known configuration a relatively complicated-designed housing for the two valves, whereby its manufacturing and machining is relatively complicated and costly. Furthermore, there is also no possibility for variations relative to the connection geometry with these known housing designs because of the pre-set flow geometry, so that connections placed in varying directions may be realized only by using additional connection pieces that would enlarge the structural dimensions in total.
It is the object of the present invention to provide an improved device of the aforementioned type wherein the disadvantages are avoided in the known corresponding device and wherein there is made possible simplification of the entire construction and easier machining, while maintaining the functional advantages, and thereby make possible a reduction in cost in general. Furthermore, a reduction in size is to be provided also by simple means at the most possible variable connection geometry.
This object is achieved according to the present invention with device of the aforementioned type wherein the housing is divided between the two valves in a dividing plane that is slanted toward the plane of the connection flanges on both sides and wherein the housing may be assembled with different relative positions of the two housing parts. The separation in the areas between the two flap valves makes basically possible optimization of the two housing parts independent from one another, especially in view of manufacturing in a cost-effective injection molding or die-casting method as well as simple construction and the establishment of different relative positions of the two housing parts by which they may be assembled and whereby different relative positions of the two assembled housing parts correspond, in any case, also to the different connection geometry through the angle of the dividing plane between the connection flanges on both sides.
In a highly preferred embodiment of the invention the dividing plane extends at an angle of 45xc2x0 to the planes of the connection flanges, which in one possible position extend in parallel with one another, and guide elements are arranged on the two housing parts that are oriented parallel to one another in the area of the dividing plane outside of the cross section of the flow, the guide elements permitting relative rotation of the two parts by 180xc2x0. An adjustment of the relative position of the two connection flanges can be achieved in a very simple manner, which is sufficient for practical use in most cases, whereby the connection flanges can extend in a parallel plane in one possible assembly position and the two connection flanges can be arranged in two planes extending perpendicular to one another in another assembly position. In one case, the entire device has a cross-flow from the inlet side to the outlet side essentially in a straight line (with a double 45xc2x0 deflection oriented in the opposite direction), whereas in the other case, the flow is two times deflected in the same direction at 45xc2x0, which is in facto a total deflection of the flow by 90xc2x0. There are now only housing parts required for these two versions that are designed the same xe2x80x94the necessary connection version is created only during assembly without further different attachments.
Cooperating recesses and projections may be provided on the guide elements of the two housing parts for determination of mutual positioning whereby in a preferred additional embodiment of the invention there are inserted preferably pin-type slide-in elements into corresponding groove-type recesses between the cooperating guide elements for mutual fixing of the two housing parts. This design makes possible simple assembly or a simple and secure attachment of the two housing parts to one another.
According to an especially preferred additional embodiment of the invention, both housing parts continually expand toward their connection flanges without back-tapering and they are manufactured by injection molding or die-casting technology and are preferably made of fiber-reinforced synthetic material or aluminum. The production of the two housing parts can thereby be further simplified and designed more cost-effective as well. Sand cores or core parts, which are complicated in their removal, are not necessary for manufacturing. Especially by manufacturing the two housing parts using the aluminum die-casting technology, the cooperating connection and sealing surfaces may be created on the housing parts in such a precise manner that additional machining is no longer necessary, which naturally reduces manufacturing costs even further.
The invention will now be explained in more detail with the help of an embodiment illustrated in the drawings.